EC220 - Quiz 5

Exhibit 6-6The life expectancy of a particular brand of tire is normally distributed with a mean of 40,000 and a standard deviation of 5,000 miles. Refer to Exhibit 6-6. What is the probability that a randomly selected tire will have a life of exactly 47,500 miles? Select one: a. .0668 b. 0 c. .9332 d. .4332

b. 0

Exhibit 6-6The life expectancy of a particular brand of tire is normally distributed with a mean of 40,000 and a standard deviation of 5,000 miles. Refer to Exhibit 6-6. What is the random variable in this experiment? Select one: a. 40,000 miles b. Life expectancy of this brand of tire c. Normal distribution d. None of the answers is correct.

b. Life expectancy of this brand of tire

Given that z is a standard normal random variable, what is the value of z if the area to the right of zis .1401? Select one: a. 2.16 b. .1401 c. 1.08 d. -1.08

c. 1.08

Exhibit 5-1The following represents the probability distribution for the daily demand of microcomputers at a local store. Demand ; Probability 0 ; .1 1. ; .2 2. ; .3 3 ; .2 4. ; .2 Refer to Exhibit 5-1. The expected daily demand is _____. Select one: a. 4 b. 2 c. 2.2 d. 1.0

c. 2.2

Assume z is a standard normal random variable. Then P(1.41 <z< 2.85) equals _____. Select one: a. .3413 b. .4772 c. None of the answers is correct. d. .8285

c. None of the answers is correct.

Exhibit 6-6The life expectancy of a particular brand of tire is normally distributed with a mean of 40,000 and a standard deviation of 5,000 miles. Refer to Exhibit 6-6. What is the probability that a randomly selected tire will have a life of at least 30,000 miles? Select one: a. .9772 b. .4772 c. .0228 d. None of the answers is correct.

a. .9772

Exhibit 6-6The life expectancy of a particular brand of tire is normally distributed with a mean of 40,000 and a standard deviation of 5,000 miles. Refer to Exhibit 6-6. What percentage of tires will have a life of 34,000 to 46,000 miles? Select one: a. 76.98% b. 50% c. 38.49% d. None of the answers is correct.

a. 76.98%

A weighted average of the value of a random variable, where the probability function provides weights, is known as _____. Select one: a. the expected value b. None of the answers is correct. c. a random variable d. a probability function

a. the expected value

A continuous random variable may assume _____. Select one: a. only integer values in an interval or collection of intervals b. all values in an interval or collection of intervals c. all the positive integer values in an interval d. only fractional values in an interval or collection of intervals

b. all values in an interval or collection of intervals

Assume z is a standard normal random variable. Then P(z≥ 2.11) equals _____. Select one: a. .9821 b. .5 c. .4821 d. .0174

d. .0174